This research project is directed toward the isolation and structural elucidation of antimicrobial compounds from marine organisms. Extracts of marine organisms are screened in the field to determine which organisms should be collected on a larger scale for study in the laboratory. The isolation of the antimicrobial compounds is accomplished using the antimicrobial assay to direct the chemical fractionation. The structural elucidations make use of all modern spectroscopic methods and, whenever possible, compounds are interrelated through chemical conversions. We are currently studying marine organisms from Palau, Gulf of California, Florida and La Jolla. We propose to complete studies of antibiotics from Reniera sp. and Udotea sp. during the next year.